Well, the first two activities can be done with both an airside and landside lounge. In fact, I wonder if you could bring non-travelling guests with you into the MEL lounge (when you are on an international ticket)?
If you are eligible for lounge access, barring being on a lounge subscription, there shouldn't be a massive queue at check-in for you.
I suppose with this setup at MEL, you will nominally leave the lounge at around T-75 to T-60, which gives you ample time to get through security and procedures in time for boarding; allow more time if you need to do TRS or any shopping.
I don't know if MEL has outbound SmartGate, but that process considerably speeds up the waiting in that part, barring those who don't know how to use the system or don't fill out the green card before they enqueue.
As it stands, this arrangement only applies to Pacific Island flights out of MEL (of which there appears to be only one destination, NAN). I guess VA didn't think too much about the demographic of people who fly this route.